This invention relates to metering valves, and in particular metering valves for liquids such as water.
Various metering valve units are known in the prior art, but have various disadvantages such as unreliable cycle times over certain limits, such as ten seconds, and a necessity to shut off the water line and remove the metering unit from the body to expose the metering screw in order to reset the cycle time. Also, in some units, metering is achieved by passing water through a compressed wad of felt. Since each cycle uses fresh water, any impurities in that water clogs the felt and lengthens the time required to pass the same amount of water. Eventually the felt is so clogged that no water passes through and the unit then runs continuously, instead of shutting off.
U.S. Pat. No. 2,918,248 of Schoenrock, Jr., issued Dec. 22, 1959, discloses a dash-pot for a flush valve which does have a closed system using water but it does not have a felt wad to vary the closing rate.
U.S. Pat. No. 4,165,857 of Morris et al, issued Aug. 28, 1979, refers to the prior art problem of gradual loss of hydraulic liquid. It solves this problem by using rolling diaphragms to contain a dash-pot liquid, in this case silicone. Adjustment of the flow rate is by means of a needle valve.
U.S. Pat. No. 3,147,827 of Weisheight, issued Sept. 8, 1964, relates to a damper for a valve which uses oil and is aimed at avoiding the problem of air getting into the damper, which would introduce a spring effect. The unit is adjustable by means of a needle valve throttle and the valve is electromagnetically actuated.
Canadian Pat. No. 675,777 of Filliung, issued Dec. 10, 1963, relates to a flush valve which is useful with salt water and other impure water supplies in that the valve mechanism is completely isolated from the water supply. A valve member 25 comprises rubber or neoprene and separates the valve mechanism from the water supply. A dash-pot mechanism 40 is used to allow the valve to open quickly but close slowly. The dash-pot is filled with hydraulic oil and the rate of closing of the valve is controlled by a needle valve member 56 rather than a wad of compressible material such as felt.
Canadian Pat. No. 765,703 of Parkison, issued Aug. 22, 1967, discloses a rotary valve. A button is pushed to actuate the valve and it does not turn. It moves a spiral cam 35 against a spring tending to bias the valve to the closed position. The valve includes a dash-pot which uses water from the supply and the water is replenished each time the valve is actuated. Adjustment of the throttling means is by means of a needle valve 44, rather than by a compressible wad of porous material.
U.S. Pat. No. 3,933,337 of Morris et al, issued Jan. 20, 1976, discloses an adjustable dash-pot mechanism which uses liquid silicone as the timing liquid. Timing adjustments are made by adjusting the position of a rod-like body within a hollow stem to vary the areas of passageways in the stem. The structure is quite complicated and includes separate metering and valve cartridges, a reservoir piston as well as metering piston and separate springs for the water valve and reservoir piston. The structure according to the invention is simpler and comprises a single cartridge. A compressible wad of porous material is used to regulate timing.